The air canister thing says GM, most likely a 83 or so 6.2L. It looks like the one in my scrap motor bin.
No It says to me GM, as I recognize it from working on them in the past. They were used in GMC and Chevys all through the 80's. If it is something you are looking to buy, check the heads, as they are prone to cracking, and the cranks are prone to breaking as well.